BY G. I. PLAYPAIR. 115 



Var. Kyoglensis, n.var. 



Forma maxima; valves lanceolatse, apicibus obtusis minime 

 protractis, quam levissime rostratis ; area central! (columella) 

 longitudinaliter divisa; membrani grosse longitudinaliter striata, 

 striis 7-8 in 10/x. 



Long. 180-200; lat. valv. 44-50, ap. 8-10 /x. 



Kyogle(41). 



Except for the longitudinal striae, this form is identical with 

 Vanheiirckia africana G. S. West, Journ. Bot., 1909, p. 246, PI. 

 498, fig. 18. 



Geuus Amphiproka Ehr 

 Amphipjigra alata var. Holdererii (Gutw.) mihi. (Pl.iv., f.l8). 



Long. 52 ji. Alee valde sinuatse. 



Lismore(l, 2). 



This form is only known besides from the Desert of Gobi, 

 Central Asia. Gutwinski (Alg. in Asia coll., p.212, Pl.ix., f.7) 

 makes it a variation of A. pahcdosa, but from the figures in Van 

 Heurck (Diat., PI. 5) it seems much nearer A. alata. It is almost 

 certain, however, that all these forms of Amphiprora are varia- 

 tions of one species. 



Genus Gomphonema Ag. 

 GoMPHONEMA AUGUR var. ROTUNDATUM (Ehr.) mihi. 

 Valvse clavatse, superne late-rotundatae, apiculo minuto inter- 

 dum instructse; lateribus superne arcuatis, inferne rapide con- 

 vergentibus, plus minus planis ; apicibus inferioribus acute- 

 rotundatis. Striae 2-3 utrinque ad centralem nodulum plerumque 

 alteris valid iores. 



Long. 30-54; lat. valv. 12-16, ap. 2-3 /x; strise 7 in 10 /x. 

 Lismore (cum sequenti). (PL iv., f.l9, 20). 



Var. AXGULATUM. (PI. iv., f.21, 22). 

 Valvse juxta nodulum centralem latissimse, hie modice angu. 

 latse et prope etiam apicem superiorem, apiculo minuto interdum 

 instructse; lateribus inferne rapide convergentibus psene planis, 

 superne arcuatis convergentibus inter angulos deplanatis. Striae 

 2-3 utrinque ad centralem nodulum plerumque alteris validiores. 



